Magnetic stirrers of this type are already known in practice. Since as a rule they do not contain any heating, the upper part of the housing can at the same time be the mounting surface for the stirring container. As a rule, the housing upper part is made of plastic, so that in the case of an aggressive medium to be stirred, there exists the danger that this upper part can be damaged by overflowing ingredients or substances, or even by aggressive vapors that are released during stirring. If the container has been wetted on the outside with the aggressive medium that is to be stirred, the contact surface is exposed to this medium for a corresponding length of time, and as a result can, in some cases, become irreparably damaged.
Attempts have already been made, therefore, to make use of an enameled upper part which still has the disadvantage that it is sensitive to impacts and requires an expensive manufacturing process. In addition to that, with all of these known solutions there exists a sealing problem between the upper and lower parts, wherein the seal is, as a rule, created by as close a fit as possible between the lower part and the upper part, and possibly by means of a labyrinth seal that is provided in conjunction therewith. As a result, an aggressive vaporized medium can make its way into the interior of the device.
A further solution provides for an upper part made of stainless steel, wherein sealing problems also arise and, in the case of highly aggressive media, the danger of corrosion exists in spite of the construction material being used. Furthermore, such a device is very expensive because of the material used.